/Engine/Plugins/Developer/Concert/ConcertMain/Source/Concert/Public/IConcertSession.h
Register a custom event handler for this session
template<typename EventType, typename HandlerType> [FDelegateHandle](API\Runtime\Core\Delegates\FDelegateHandle) RegisterCustomEventHandler ( HandlerType * Handler, typename [TConcertRawSessionCustomEventHandler](API\Plugins\Concert\TConcertRawSessionCustomEventHan-)< EventType, HandlerType >::FFuncType Func )